This image released by NBC shows host Jimmy Fallon dressed as a mom, left, dancing with first lady Michelle Obama during an appearance of "Late Night with Jimmy Fallon," Friday, Feb. 22, 2013 in New York. Obama returned to the show to promote her "Let's Move" campaign and to perform in a sketch called "Evolution of Mom Dancing," airs tonight at 12:35am ET on NBC. (AP Photo/NBC, Lloyd Bishop)

Associated Press
This image released by NBC shows host Jimmy Fallon dressed as a mom, left, dancing with first lady Michelle Obama during an appearance of "Late Night with Jimmy Fallon," Friday, Feb. 22, 2013 in New York. Obama returned to the show to promote her "Let's Move" campaign and to perform in a sketch called "Evolution of Mom Dancing," airs tonight at 12:35am ET on NBC.   (AP Photo/NBC, Lloyd Bishop)
This image released by NBC shows host Jimmy Fallon dressed as a mom, left, dancing with first lady Michelle Obama during an appearance of "Late Night with Jimmy Fallon," Friday, Feb. 22, 2013 in New York. Obama returned to the show to promote her "Let's Move" campaign and to perform in a sketch called "Evolution of Mom Dancing," airs tonight at 12:35am ET on NBC. (AP Photo/NBC, Lloyd Bishop)